This invention relates to a molding equipment for making a composite molded body. More specifically, this invention relates to the manufacture of a composite molded article where a desired skin material is placed on the surface of a plastic substrate by injection-compression molding. The skin material is placed on the surface of the plastic substrate for decorative purposes or to add a desired functional property. This invention also relates to the improvements of molding equipment for making composite molded article and the method for using such molding equipment.
A conventional composite molded article may be exemplified by the interior material used in automobiles and furniture. Usually, such a composite molded article has a plastic substrate covered by a highly decorative skin material such as PVC leather, felt, and the like, using adhesive glue. Very often, since a process of gluing skin material onto plastic substrate is time consuming, the design has to be limited, and the possibility of producing inferior goods and the cost is high. These have been the problems.
For this reason, it has been proposed that a skin material covered composite molded article may be obtained from a stamping molding machine specially designed for this purpose with skin material placed in the mold prior to molding. After covering the mold with skin material, the melted resin is injected into the mold, and the mold is then clamped.
However, when such a prior art stamping molding is used, as soon as the, melted resin is injected into the mold, a portion of the injected resin starts contacting the skin material right away. On the contrary, since the skin material becomes fully covered by the resin only when the clamping is completed, the contact time between the resin and the skin material becomes partially different. In some areas, the resin and the skin material are contacted at high temperature, while in some other areas, the resin and the skin material are contacted when the temperature has dropped to some extent. This has become a drawback because a uniform article cannot be obtained particularly when the scale of molding is large. When it is attempted to overcome this drawback by placing the melted resin evenly on the skin material, the time needed for molding becomes too long, and the deterioration in the physical properties of welded portions due to multiple resin supply results in another problem.
In order to solve the problems noted above, it has been proposed to use a special purpose stamping molding machine which injects and coats the melted resin substantially evenly onto the surface of the skin material and then molds. However, the equipment is highly expensive, the molding cycle is long, and suitable resin materials are limited. In addition, the problem of which the temperature of the resin becomes nonuniform at the time of molding, cannot be completely solved.
Also, with such a special purpose stamping molding machine, the high price of the machine is not the only problem. It is also a problem that a very long time is needed before an article with good quality can be obtained.
In order to solve the problems noted above, it has been disclosed by the present inventors that without using a high cost, special purpose stamping molding machine, a totally uniform composite molded article can be obtained in a short time using a low cost, general purpose injection molding machine. The molding equipment and the method of using this machine have been disclosed in Japanese Patent Laid Open Publication Hei 5-220094. The molding equipment has been characterized by comprising:
(a) a fixed mold having a convex portion integral with a gate; said convex portion being formed according to the shape of the molded article; said gate being used for injecting melted resin into a resin molding space, i.e. a cavity; PA1 (b) a movable side mold capable of being moved close to and away from said fixed mold; said movable mold consisting of a concave portion; said concave portion being formed according to the shape of said molded article; said concave portion being inlaid with said convex portion of said fixed mold to form said resin molding space when said molding equipment is clamped; PA1 (c) a supplemental mold being mounted between said fixed mold and said movable mold; said supplemental mold being movable toward and away from said fixed mold and said movable mold; said supplemental mold having an opening; said opening being smaller than the opening of said concave portion of said movable mold; said opening being sufficiently large for said convex portion of said fixed mold to penetrate, when said molding equipment is clamped; and PA1 (d) a skin material setting frame being mounted between said fixed mold and said supplemental mold; said skin material setting frame being capable of setting a skin material. PA1 (a) a fixed mold having a convex portion integral with a gate; said convex portion being formed according to shape of molded article; said gate being used for injecting melted resin into a resin molding space; PA1 (b) a movable side mold capable of being moved close to and away from said fixed mold; said movable mold consisting of a concave portion; said concave portion being formed according to the shape of said molded article; said concave portion being inlaid with said convex portion of said fixed mold to form said resin molding space when said molding equipment is clamped; PA1 (c) a set of slide cores being mounted between said fixed mold and said movable mold; said slide cores being movable toward and away from said fixed mold; said slide cores consisting of a plurality of members; said plurality of members being movable toward and away from each other along a near right angle direction of the moving direction of said movable mold; said slide cores forming an opening at the center when said said plurality of members being moved close to each other; said opening being smaller than the opening of said concave portion of said movable mold; said opening being sufficiently large for said convex portion said fixed mold to penetrate, when said molding equipment is clamped; and PA1 (d) a skin material setting frame being mounted between said fixed mold and said slide cores; said skin material setting frame being capable of setting a skin material. PA1 (a') setting a desired skin material in said skin material setting frame; said skin material setting frame being brought to a position faced to said convex portion of said fixed mold; PA1 (b') drawing said slide cores reciprocally toward a center portion to form an opening; said opening being sufficiently large to allow said convex portion of said fixed mold to penetrate through; PA1 (c') moving said movable mold, said slide cores, and said skin material setting frame toward said fixed mold; placing said slide cores, and said skin material setting frame between said fixed mold and movable said mold; and closing said slide cores and said skin material setting frame in their pre-determined positions; PA1 (d') filling melted resin into a forming space through a gate of said fixed mold; PA1 (e') moving said movable mold further toward said fixed mold; and clamping said molds under a low pressure; PA1 (f') cooling; PA1 (g') drawing said slide cores reciprocally away from the center portion of the opening; PA1 (h') releasing said skin material from said skin material setting frame; PA1 (i') moving said movable mold away from said fixed mold; and opening said mold; PA1 (j') separating molded article and said mold by a protruding mechanism mounted in fixed side; PA1 (k') removing said molded article; and PA1 (l') returning said skin material setting frame to its original skin material setting position. PA1 said movable mold and said slide cores are separately movable toward and away from said fixed mold. PA1 said slide cores is mounted on said movable mold; and PA1 said movable mold and said slide cores are together movable toward and away from said fixed mold. PA1 a roundness is added to a angular portion of an edge portion; PA1 said edge portion forms an opening when each of said slide cores is drawn toward the center portion; and PA1 said anglar portion is on a side facing said movable mold. PA1 a movable slide frame is added to an edge portion; PA1 said edge portion forms an opening when each of said slide cores is drawn toward the center portion; and PA1 said movable slide frame is capable of moving toward and away from a direction of a center of said opening. PA1 a seat portion is continuously placed on a bottom portion of said convex portion to prevent the formation of wrinkles on said skin material at an end portion of a molded product; PA1 said seat portion has an outside shape same as the shape of said convex portion; and PA1 said convex portion of said fixed mold has a height sufficiently higher than the maximum intrusion height of said convex portion of said fixed mold inside said concave portion of said movable mold during molding. PA1 when the maximum length (m) in either the vertical or horizontal direction of the projecting area of a molded product is longer than said maximum intrusion height (h) of said convex portion of said fixed mold inside said concave portion of said movable mold during molding, said maximum length (m) makes the height of said seat portion (g) fulfill a relation expressed by g/h; and PA1 said g/h is from about 0.5 to about 2.0. PA1 said g/(h+d) is from about 0.5 to about 2.0. PA1 (a') setting a fiber based skin material as said skin material in said skin material setting frame; said skin material setting frame being brought to a position faced to said convex portion of said fixed mold; PA1 (b') drawing said slide cores reciprocally toward the center portion to form an opening; said opening being sufficiently large to allow said convex portion of said fixed mold to penetrate through; PA1 (c') moving said movable mold said slide cores and said skin material setting frame toward said fixed mold; placing said slide cores, and said skin material setting frame between said fixed mold and movable said mold; and closing said slide cores and said skin material setting frame in their pre-determined positions; PA1 (c'-1) releasing said skin material from said skin material setting frame; PA1 (d') filling melted resin into a resin forming space through a gate of said fixed mold; PA1 (e') moving said movable mold further toward said fixed mold; and clamping said molds under a low pressure; PA1 (f') cooling; PA1 (g') drawing said slide cores reciprocally outward (away from center portion of the opening); PA1 (h') moving said movable mold away from said fixed mold; and opening said mold; PA1 (i') separating molded article and said mold by a protruding mechanism mounted in fixed side; PA1 (j') removing said molded article; and PA1 (k') returning said skin material setting frame to its original skin material setting position.
According to this molding equipment, the special purpose, high cost stamping molding machine is no longer needed in a large scale production of composite molded articles. With this molding equipment, a large scale production of composite molded articles can be carried out using a low cost, general purpose injection molding machine. In addition, there are many advantages in using this molding equipment. For example, the resin does not leak and the end of the skin material is surely molded onto the plastic substrate. The wrinkles on the skin material does not occur. The equipment is simple. The post-treatments after molding are easy. The molding cycle is completed in a short period of time. However, the operating efficiency of this molding equipment was not good because the supplemental mold and the movable mold must be reciprocated more than one time during molding operation.
Furthermore, concerning the manufacture of a so-called "decorativeness-added" composite molded article as mentioned above, a so-called "decorative, one-piece molding method" has become widely used in recent years. The decorative, one-piece molding method simultaneously gives shapes to the skin material and the thermoplastic resin during molding to form an one-piece molded article in one operation. However, since the shape-giving of the skin material and the molding of the thermoplastic resin have to be carried out within one molding procedure to give an one-piece molded article, many cases using such decorative, one-piece molding method encounter a problem in the appearance of the molded article produced. Very often the appearance of the molded article produced is damaged because of the formation of wrinkle in the skin material of the product. To resolve such a problem, the methods described below have been considered.
For example, there is a method in which a skin material is put in the mold after a preliminary shape-giving, and one-piece molding is then carried out. Definitely, in the one-piece molding of the armrest For use in an automobile, as disclosed in Japanese Patent Laid Open Publication SHO 62-256619, a preliminary shape-giving is first carried out to give the shape of the product to a skin material. After the preliminary shape-giving the skin material is then set in the cavity of the mold for use in injection molding. The resin is injected into the cavity and the skin material is pushed and pressed onto the cavity mold. Finally, one-piece, molding is carried out. With carrying out such a preliminary shape-giving first, there has become no more occurrence of wrinkles on the skin material of the product. However, the advantage of one-piece molding is lost because now the preliminary processing is increased, and the equipment and the like for the preliminary shape-giving operation have become necessary.
Furthermore, as a development of the preliminary shape-giving of the skin material, a method in which the preliminary shape-giving and the one-piece molding can be carried out in a series of equipments, has also been proposed (cf. Japanese Patent Laid Open Publication HEI 5-253939). In this method, the skin material is first placed in a mold for use in vacuum molding to have the preliminary shape-giving of the skin material carried out by vacuum molding. While keeping the skin material covering the wall of the cavity side mold, the mold is rotated to face the core mold for use in injection molding, and one-piece molding is then carried out. However, this method is not desirable because the equipment needed in this method is large in scale and is complicated, and a big capital investment is necessary.
As a measure to solve the failure in the appearance of the product due to wrinkles and the like, a method in which a product without the Failure caused by wrinkles and the like, can be obtained by one-piece molding after applying some tension force to a skin material without preliminary shape giving. This method has been proposed in Japanese Patent Laid Open Publication SHO 60-220717. However, the tension force has to be adequately applied according to the thickness and the kind of the skin material. Also, the modification of the tension force to match the shape-giving condition is an extreme difficulty. An equipment which corresponds with all tension force ranges is complicated, and is practically difficult.
As described above, in the skin material-used, decorativeness-adding, one piece molding, although a product with an excellent appearance, i.e., without wrinkles and the like, can be obtained if the preliminary shape-giving of the skin material is carried out first, there is an increase in the number of operations needed in the course of production. Also, when a skin material is used without any preliminary shape-giving, the wrinkles and the like tend to form easily if the skin material is to be disposed in the mold as is. Therefore, it is necessary that some kind of tension force be applied to the skin material. However, this is very difficult since the equipment needed for generating such a tension force, as well as the determination and the setting of the value of the tension force have become complicated. In short, in the decorativeness-adding, one-piece molding, in order to obtain an excellent product with a wrinkle-free appearance, there are problems remained unsolved. Such problems include the increase in the number of operations needed in the course of production, the complication in equipment, and the like.